1. Field of Invention
The present invention relates to aviation obstruction lights, specifically the control of aviation obstruction lights for compliance with United States and international regulations.
2. Description of the Related Art
Aviation obstruction lights have been commonly used in conjunction with various aviation obstructions, such as radio and television broadcast towers and various telecommunications towers, buildings or other structures, and such aviation obstruction lights will become even more commonly used and seen as more broadcast and telecommunications towers are built. With the use of the aviation obstruction lights comes a need for controlling the lights to ensure that the lights are working properly and a need to control the light pattern produced by the aviation obstruction lights.
On a typical broadcast tower, there are more than one evenly spaced levels on the tower that require lighting. The top level is most often a flashing light. The next lower level is usually a steady-on light. The third level from the top flashes and the next is steady-on again. And so on. The flashing lights are normally required to be brighter by using higher wattage lamps. Often, all of the stead-on lights can be controlled by a single controller. Since the wattage is higher on the flashing lights, multiple controllers may be required here.
To minimize costs, obstruction lights that are intended to be steady-on are often wired directly to the power source via a relay that is activated by a remote day/night photocell. This short-cut technique has several serious disadvantages. First, when the lights are initially energized, the inrush of high current onto cold lights causes severe thermal stress on the filaments. Especially on cold days, incandescent lamp filaments are often destroyed when this occurs. A gradual means of illumination is much more desirable. A second disadvantage is that the expected wattage use must still be monitored by another peripheral means to comply with agency regulations. When an individual bulb has failed, the wattage use will be less and this condition must be detectable. Burned out lights must be replaced.
One previous approach to the control issue has been the use of a control system which utilizes a remote module located at each light with a group of remote modules being controlled by a main module and a main station located on a ring network (U.S. Pat. No. 5,644,304) or using a vault computer as a central control for remote and master control modules (U.S. Pat. No. 5,926,115). A problem with this structure is the size and numerosity of components, for example, many remote modules, main modules, and main stations are required in the ring network, and that components, such as the main stations or vault computers, are relatively large.
A secondary problem with the described structure is that troubleshooting of a problem with the control system becomes problematic since there are many components which may malfunction and even within the various components, there may be numerous wires and smaller components which need to be checked and double checked for problems. Also, with numerous components comes a higher cost for those components.
Yet another problem with the above-described structure is the complexity of the structure. Any time that a problem would occur with the control system, an engineer or technician would need to be required to come to the site of the control system and trouble shoot each component in order to even determine what is the problem before any solution could be implemented. The operator or the owner of the control system, such as the airport or the owner of the tower, would be unable to determine the problem or isolate the problem before calling upon a repair crew. Thus, this structure presents numerous problems which affect operation of the aviation obstruction lights.
Previous approaches also have the problem of when one portion of the network fails, the entire network or at least a larger portion of the network also fails, thereby resulting in inconvenience, from having a non-operating system, and potential monetary fines and other penalties imposed by the regulating authorities for having such a non-operating system. An associated problem exists when the portion that fails is a main station (U.S. Pat. No. 5,644,304) or a vault computer (U.S. Pat. No. 5,926,115) since the loss of those components could result in non-operation of a much larger portion of a network than the failure of a remote module or controller. When such a large component fails, the operation of the aviation obstruction lights needs to be interrupted by shutting down the network to facilitate repair or replacement of the failed components.
A control system for aviation obstruction lights which is not complicated, is less difficult to debug and which does not require expensive components or significant downtime would be desirable.